Various techniques for mounting electrical components on printed circuit boards are known in the art. One such technique involves the insertion of the lead ends of the electrical components through plated openings to the opposite surface of the printed circuit boards and, thereafter, soldering the inserted ends to secure the electrical component to the board and make the required electrical connections.
Another technique, so-called surface mount technology (SMT), involves electrical components that are mounted directly onto the surface of the printed circuit board without leads penetrating to the opposite side of the printed circuit board. More specifically, in a typical surface mount process, the printed circuit board has printed on the surface thereof circuit traces and contact/mountings or conductive "pads". A surface mount electrical component having a plurality of leads is placed on the pads. Sometimes an adhesive is used to hold the surface mount component in position on the circuit board. Solder may have been applied to either the plurality of leads of the electrical component or the pads prior to placement of the electrical component on the pads. When all components are in place on the printed circuit board, heat energy is applied to solder and effect electrical and mechanical connections between the leads of the electrical components and the pads and traces of the printed circuit board.
There are various types of surface mounted electrical components and various types of lead structures thereof. The present invention is directed to surface mount electrical components which have inwardly extending J-shaped leads and to the replacement and repair of such J-lead surface mount electrical components. The present invention also has application to initial manufacturing of a SMT type printed circuit board, i.e., the initial loading of the electrical components on the SMT printed circuit board.
Existing procedures for repairing and replacing J-lead SMT electrical components involve removing the failed electrical component and soldering a new electrical component onto the printed circuit board. In practice, such repair or replacement presents several difficulties. One of such difficulties relates to the need to precisely locate the electrical component's J-leads over the contact/mounting pads on the printed circuit board to insure reliable solder joints. Maintaining the electrical component's position over the pads is important to insure that the component's J-leads do not move off of the pads prior to and during the soldering operation. Still another difficulty relates to the nature of the design of SMT J-leads. The solder joints at the J-leads are located under the electrical component body and thus are at least partially obscured from access and sight during soldering operations. This last difficulty is exacerbated on densely populated printed circuit boards.
SMT replacement systems currently available include expensive and complex equipment to meet the difficulties described above. The use of these complex systems usually requires the service technician in the field repairing an SMT printed circuit board to return the printed circuit board to the factory or to a service center for SMT electrical component repair or replacement.
Accordingly, there is a need for a simple, but reliable, and inexpensive technique for accurately locating the J-leads of SMT electrical components and for soldering the J-leads to the printed circuit board, either during initial manufacture of a SMT type printed circuit board or when servicing SMT printed circuit boards in the field.